With summer upon us, it’s the season for outdoor events – street fairs, marathons and music festivals. Many of these gatherings will require structures like tents, canopies and stages. While structural engineers most often deal with permanent structures that stay in place for decades or centuries, they may be enlisted to ensure that these temporary structures are safe for human habitation.
The world of permanent structures is full of international standards and codes that govern the proper way to design and erect a building. Nearly all states and municipalities have adopted ASCE 7, the American Society of Civil Engineers’ definitions for the minimum design loads on buildings and other structures. The level of certainty that comes from unified standards allows you to be reasonably certain that a new building in Florida is just as structurally sound as one in New York.
But those standards are considerably less defined when it comes to temporary structures. While most temporary structures must conform to local building codes, those codes (and their enforcement) can vary widely between jurisdictions. For decades, engineers and event organizers were typically left to use their best judgement about whether a structure was safe. For lack of a clearer standard, engineers have typically used ASCE 37, which was written to address acceptable loads on structures that are under construction. According to the standard, building under construction only has to withstand 56 percent of wind loads compared to the finished product, since the likelihood of an extreme weather event is lower during the relatively brief construction period. A temporary structure is similar, the reasoning goes, in that it’s not as likely to see that generational storm.
Several high-profile stage collapses in recent years have led to calls for stricter structural standards and clearer rules on when events should be cancelled due to wind. Seven people were killed in 2011 when a stage collapsed at the Indiana State Fair, leading to a $50 million settlement. The event led to the establishment of the Event Safety Alliance, which has issued a set of standards they hope will be adopted around the country. Several bands, including Linkin Park and Phish, have unilaterally required guarantees of strict structural standards and clear emergency plans in their contracts before performing and even hired meteorologists to travel with the band and monitor weather.
While standards for temporary construction begin to become clearer, event organizers are continuing to experiment with unique temporary structures and construction methods at music festivals around the country:
• 3M LifeLab Pavilion: 3M tried something truly groundbreaking for SXSW 2015, a popular music festival in Austin, Texas. The entire structure was made from aluminum pipes along with 1,200 connecting joints that were produced entirely with a 3D printer. The interior was finished with a glossy white version of 3M’s Di-Noc architectural finish. Interior columns featured film that changed color depending on the angle it was being viewed, as well as the ambient light in the tent. Here’s a time lapse video of its construction.
• Lightweaver: This 45-foot-high art installation produced by Alexis Rochas and Andreas Froech was all the talk of Coachella 2014. The structure, which looks like a contorted knot or double helix, was made of an intricate series of space frames, with the connecting nodes precisely drilled by an automotive robot. The skin of the installation was used as a canvas for a projected multimedia light show.
• Burning Man: Temporary structures are central to the identity of this iconic art festival, in which a bustling of city of more than 60,000 is set up and taken down in a matter of weeks. Art installations vary from an 80-foot-tall wooden man to elaborate temples with 126-foot-tall hexagonal towers. Beware, though: the Black Rock Desert is known for its 75-mph winds, so you’ll need a solid foundation.
About the Author
Caleb Heeringa, Communications Coordinator | Caleb enjoys immersing himself in the A/E/C industry and informing audiences about DCI’s contribution to state-of-the-art structural development. Preferring a conversational style, he naturally narrates the firm’s design approach and project details to professionals in other industries. With a knack for adventure, he enjoys international travel and exploring the back corners of Washington’s wilderness.